Core for concrete pipe molding machines



Feb. 18', 194-1. 0. TUERCK CORE FOR CONCRETE PIPE MOLDING MACHINES Filed April 22, 1940 [r2 van for Oscar Tuerck Aiol neys Patented Feb. 18, 1941 UNITED STATES CORE FOR CONCRETE PIPE MOLDING MACHINES Oscar Tuerck, Portland, reg'., asslgnor to Tuerck- Mackenzie Company, Portland, 0reg., a corporation of Oregon Application April 22, 1940, Serial No. 330,826

Claims.

This invention relates in general to concrete pipe molding machines, for example, of the type shown in United States Letters Patent, No. 1,523,937, issued January 20, 1925, and in United 5 States Letters Patent, No. 2,185,613, issued January 2, 1940.

It is customary in such concrete .pipe molding machines to provide a stationary core for the mold, and a rotating outer shell. The concrete mixture, composed of sand, gravel, cement and water, is slowly fed into .the annular space between the core and the rotating shell, while vertically reciprocating tamping bars compact the concrete mixture. Due to the high abrasive nature of the materials used in the concrete mixture, the rotation of the shell and mixture around the inner stationary core of the mold causes wear to occur on the outer cylindrical surface of the core, this wear is of course greatest in the bottom of the core and gradually decreases towards the top of the cylindrical .core surface. As

a result .the cores in such machines must be replaced fairly frequently or else this wearing 'of the core surface will result in too great a variation in the interior diameter of the concrete pipe produced in the mold.

The primary object of this invention is to provide an improved core, the life of which may be considerably prolonged beyond the life of ordinary cores heretofore used. This object is accomplished in part by forming the core in such manner that its cylindrical shell may be composed of metal having Brinell hardness, for example, of 500 which it has been previously considered impractical to use in cores of the con-- ventional type.

In conventional cores for concrete pipe machines, the core casting is turned to the required size as on a lathe, the ends of the core are planed flat, the bottom end is bored to fit a trunnion on which the core is supported during the molding of the pipe, and numerous holes are drilled and tapped in the upper end of the core for attaching a stem, by which the core is lifted, and for attaching additional form members for shaping the top or bell-end of the concrete pipe. These conventional cores must therefore be cast of metal which is not too hard to prohibit such Various machining operations from being performed with ordinary cutting tools and drills. The two requirements of low hardness for machineability and of high hardness for resisting the abrasive action of the concrete mixture have presented a problem heretofore unsolved in conventional cores. With my improved core however, it is possible to use a metal of the highest hardness.

A further object of this invention is to provide a core which is readily reversible so that such wear as occurs on the outside cylindrical surface may be more evenly distributed over the entire surface; this also .contributing to prolong the life of the core.

The manner in which I attain these and incidental objects in my improved core will be explained briefly with reference to the accompanying drawing in which:

Figure 1 is an elevational view, partly in section, of the mold and core and related parts of a machine for fabricating cementitious pipe;

Figure 2 is a plan of the core as viewed from the plane of dine 22 of Figure 1;

Figure 3 is an enlarged vertical section of the core itself, removed from the pipe molding machine;

Figure 4 is a sectional plan taken on the line 4--4 of Figure 3; and

Figure 5 shows one of the inserts set in the internal flanges of the core during the casting of the core.

In Figure 1 my improved core I0 is shown in place in a conventional type of pipe-forming machine (only related parts of the machine being shown), which machine includes a rotatable outer shell a of the mold concentrically disposed about the stationary core 10. The outer shell a is detachably clamped to .a base plate b. The base plate b is journaled on a trunnion c and is drivingly rotated through .the media of gear teeth d and an engaging motor-driven pinion e.

The base plate b is in turn formed with a trunnion f which enters the bottom end of the core l0 and supports the core in concentric relationship to the outer shell a of the mold.

A pair of horizontal parallel bars 9 extend from the frame of the machine (not shown) and are detachably secured, as by a bolt h, to the hoisting stem 1' of the core. The hoisting stem 2' is formed with a bottom flange 7' and the core is attached to this flange by means of cap screws it. These bars 9 thus hold the upper end of the core in the proper central position in the mold and also prevent the core from turning when the rest of the mold and the concrete mixture within the mold are rotated. The stem 1' of the core is usually extended upwards through a fixed frame member such as l, and may be fitted with a yolk m to carry a sheave n which forms part of suitable tackle for raising the core from the mold when the pipe and shell are to be removed.

In Figure 1 the mold is shown partly filled proportions, is slowly fed into the annular space between the stationary core l and the rotating outer shell 0.. During the feeding of the concrete mixture into this annular space, the vertically reciprocating tamping bars q, located on opposite sides of the circular strip of metal reinforcement p of the pipe, compact the mixture while the mixture gradually accumulates in the mold.

My improved core it comprises a tubular casting H (see Figure 3), preferably cast in one piece, with annular integral flanges [2 formed near each end, substantially as shown in Figure 3. The distance of each flange l2 from the corresponding open end of the tube casting is made to coincide with the thickness of end plates l3 which complete the core. The tubular casting I l is otherwise of uniform cross-section throughout its entire length and is symmetrical in every respect.

This tubular casting ll of my core I make from alloyed metal having a maximum potential' hardness. Since the degree of hardness of this casting will preferably be considerably in excess of the range of hardness for eflicient machining with ordinary turning, boring, drilling and tapping tools, I finish the outer cylindrical surface of my core to the required dimensions by using surface grinding and. polishing machines. Also, since the internal flanges I2, being integral with the tubular shell, are formed of the same hard metal, I provide inserts I4 symmetrically-arranged and set in these flanges during the casting process. The inserts I4 are made of softer metal and are preferably made spool-shaped or with double flanges, as shown in Fig. 5, with the perimeters of the flanges made polygonal, as shown in Fig. 4, so that the inserts M will be firmly secured in place. These inserts are then drilled to receive the screws l5 for anchoring the end plates [3 in position.

The end plates 13 are also made of softer metal than the tubular casting H. The end plates 13 are identical and interchangeable.

Each end plate is provided with a concentric bore I6 adapted to fit the stem of the trunnion 1 (Figure 1), and each end plate 13 also has suitable threaded holes l1 (Figure 3) to accommodate the screws 7c (Figures 1 and 2) by which the flange 7' of the hoisting stem 1' is secured to the top of the core. Further threaded holes may easily be provided in the end plates for supporting brackets for special forms used in shaping the top or bell-end of the pipe when these are desired.

It will be apparent, from Figure 3, that my core is easily reversible. All that is necessary is to detach the flange 7' from the upper end plate or to remove both end plates and reverse the tubular casting H. This reversing of the tubular casting H makes it possible to have the wear distributed over the entire outer surface of my core evenly instead of limiting the greater wear to one end of the core. At the same time the extremely hard polished surface of the tubular casting ll minimizes the abrasive wear of the core, while the form in which my core is made enables metal of any desired hardness to be used in the tubular casting as explained.

I have found that metal with a Brinell hardness of 500 or Shore hardness of 70, or Rockwell hardness of 50, may satisfactorily be used for this tubular casting of my core, but that metal of considerably less hardness should then be used for the inserts M in the flanges of the casting and for the two end plates of the core. However, it is not my intention to limit my invention to the use of any particular kind or quality of metal. Furthermore, various modifications might, of course, be made in the shape and structure of the end plates and of the associated parts, without departing from the principle of my invention. It is not my intention to limit my invention otherwise than as set forth in the attached claims.

I claim:

1. In a core for a concrete pipe molding machine, a tubular casting formed of metal having a high degree of hardness, end plates removably inserted in the ends of said casting, said end plates made of softer metal than said casting, end-plate-supporting members located within said tubular casting and integral with said casting and means attaching said end plates to said members, whereby core holding and moving means in said machine are attached to said end plates Without necessitating any drilling or machining of said tubular casting and said tubular casting may readily be reversed to equalize the wear on the surface at both ends of said casting in said machine. I

2. In a core for a concrete pipe molding machine, a tubular shell of uniform thickness having a high Brinell hardness, flanges on the interior of said tubular shell formed integral with said shell, said flanges located adjacent the ends of said shell respectively, inserts of softer metal set in said flanges, end plates removably inserted in the ends of said shell, means securing said end plates to said flanges respectively, said means including screws passing through said plates and into said inserts in said flanges, whereby core holding and moving means in said machine are attached to said end plates without necessitating any drilling or machining of said tubular shell and said tubular shell may readily be reversed to equalize the wear on the surface at both ends of said shell in said machine.

3. A reversible core for a concrete pipe molding machine including, a tubular shell of uniform thickness formed from cast metal having a high Brinell hardness, a pair of annular flanges on the interior of said tubular shell formed integral with said shell, said flanges located adjacent the ends of said shell respectively, end plates removably inserted in the ends of said shell, said end plates made of softer metal than said shell, means securing said end plates to said flanges, whereby core holding and moving means in said machine are attached to said end plates without necessitating any drilling or machining of said tubular shell.

4. A core for a concrete pipe molding machine including, a tubular shell of uniform thickness having approximately 500 Brinjell hardness, flanges on the interior of said tubular shell formed integral with said shell, said flanges located adjacent the ends of said shell respectively, said flanges being identical, end plates removably inserted in the ends of said shell,

said end plates made of softer metal than said shell, means securing said end plates to said flanges, whereby core holding and moving means in said machine are attached to said end plates without necessitating any drilling or machining of said shell and said tubular shell may readily be reversed to equalize the wear on the surface at both ends of said shell in said machine.

5. A core for a concrete pipe molding machine including, a tubular shell of uniform thickness formed from cast metal having a high Brinell hardness, a pair of annular flanges on the interior of said tubular shell formed integral with said shell, said flanges located adjacent the ends of said shell respectively, said flanges being identical, inserts of softer metal set into said flanges, end plates removably inserted in the ends of said shell, said end plates made of softer metal than said shell, means securing said end plates to said flanges respectively, said means including screws passing through said plates and into said inserts in said flanges, whereby core holding and moving means insaid machine are attached to said end plates without necessitating any drilling or machining of said tubular shell, and said tubular shell may readily be reversed to equalize the wear on the surface at both ends of said shell in said machine.

OSCAR TUERCK. 

